1. Field of the Invention
The present invention is generally in the field of electronic circuits and systems. More specifically, the present invention is in the field of communications circuits and systems.
2. Background Art
Transceivers are typically used in communications systems to support transmission and reception of communications signals through a common antenna, for example at radio frequency (RF) in a cellular telephone or other mobile communication device. A transmitter routinely implemented in such a transceiver in the conventional art may utilize several processing stages to condition and preamplify a transmit signal prior to passing the transmit signal to a power amplifier (PA). In many applications, it may be advantageous to adjust the transmit power level of the PA in order to conserve power, and a peak detector may be implemented to help enable that process. For example, the transmitter may adjust, e.g., reduce, its transmit power according to the peak value of a communication signal as measured by its peak detection circuit.
A peak detector implemented in a transmitter is typically designed to provide a direct-current (DC) output corresponding to the peak value of a modulated and preamplified transmit signal provided as an input signal to the peak detector. Conventional peak detectors normally provide no additional amplification, and in practice may attenuate the input signal. Moreover, conventional peak detectors are well known to suffer the dual drawbacks of low sensitivity and low dynamic range. At best, conventional peak detectors provide a DC output approaching the peak value of their input signals, but that may occur only for input signals having an optimized frequency range. Consequently, conventional peak detectors may not reliably provide accurate information about transmit signal strength and thereby frustrate power conservation objectives, which may be particularly undesirable when the transceiver is implemented in a mobile communication device powered by a battery.
Thus, there is a need to overcome the drawbacks and deficiencies in the art by providing a peak detector having an extended dynamic range, suitable for implementation as part of a more modern mobile device transceiver.